Knee tensioner with digital force and displacement sensing

Abstract

A tensioner tool for assessing joint laxity is disclosed. The tensioner tool comprises a pair of pivotally coupled arms, each arm comprising a proximal handle portion, a distal portion, and an insertion tip selectively coupled to the distal portion. The pair of arms pivot between a compressed configuration for insertion within the joint and an expanded configuration for distraction of the joint by applying a force to the handles, thus spreading the insertion tips. The tensioner tool also comprises a force sensor configured to measure the force applied to the handle portion and a positional sensor configured to measure a separation distance between the pair of arms. The tensioner tool also comprises a processor configured to calculate a distraction force at the insertion tips based on the measured force and to calculate a tip distance between the insertion tips based on the measured separation distance.

1 . A tensioner tool for assessing laxity of a joint including first and second bones, the tensioner tool comprising:
 a pair of arms pivotally coupled at a pivot joint, each arm including a proximal handle portion, a distal portion, and an insertion tip selectively coupled to the distal portion, wherein the pair of arms are configured to pivot about a pivot axis between a compressed configuration for insertion between the first and second bones and an expanded configuration for distraction of the first and second bones in response to a force applied to at least one of the proximal handle portions, wherein a tip distance between the insertion tips is greater in the expanded configuration than in the compressed configuration;   a force sensor coupled to one of the pair of arms and configured to collect force data related to the applied force;   a positional sensor configured to collect separation data related to a separation distance between the pair of arms;   a processor; and   a non-transitory, computer-readable medium storing instructions that, when executed, cause the processor to:
 receive the force data from the force sensor, 
 calculate, based on the force data, a distraction force exerted to the first and second bones by the insertion tips, 
 receive the separation data from the positional sensor, and 
 calculate the tip distance based on the separation data. 
   
     
     
         2 . The tensioner tool of  claim 1 , wherein for each arm, the distal portion comprises a through-hole configured to mate with a shaft of the insertion tip to selectively couple the insertion tip to the distal portion. 
     
     
         3 . The tensioner tool of  claim 2 , wherein for each arm:
 the insertion tip is configured to be received within a first end of the through-hole and extend substantially in a first direction from the distal portion; and   the insertion tip is configured to be received within a second end of the through-hole and extend substantially in a second direction, opposite the first direction, from the distal portion,   wherein the first direction and the second direction are substantially parallel to the pivot axis.   
     
     
         4 . The tensioner tool of  claim 1 , wherein for each arm, the insertion tip is configured to rotate about a tip axis with respect to the distal portion when coupled to the distal portion. 
     
     
         5 . The tensioner tool of  claim 4 , wherein the tip axis is substantially parallel to the pivot axis. 
     
     
         6 . The tensioner tool of  claim 1 , wherein each insertion tip is disposable. 
     
     
         7 . The tensioner tool of  claim 1 , wherein:
 the insertion tip of a first arm of the pair of arms comprises a single prong; and   the insertion tip of a second arm of the pair of arms comprises a pair of prongs.   
     
     
         8 . The tensioner tool of  claim 1 , wherein each insertion tip comprises a geometry configured to conform to a surface of at least one of the first and second bones. 
     
     
         9 . The tensioner tool of  claim 1 , wherein the force sensor comprises a strain gauge. 
     
     
         10 . The tensioner tool of  claim 1 , further comprising a magnet coupled to a first arm of the pair of arms,
 wherein the positional sensor comprises a Hall effect sensor coupled to a second arm of the pair of arms.   
     
     
         11 . The tensioner tool of  claim 1 , wherein the positional sensor comprises one or more of a rotary encoder and a rotary potentiometer. 
     
     
         12 . The tensioner tool of  claim 11 , where the positional sensor is disposed within the pivot joint. 
     
     
         13 . The tensioner tool of  claim 1 , further comprising a display configured to display one or more of the distraction force and the tip distance. 
     
     
         14 . The tensioner tool of  claim 13 , wherein one or more of the display, the processor, and the non-transitory, computer-readable medium are each disposed on the proximal handle portion of one of the pair of arms. 
     
     
         15 . The tensioner tool of  claim 1 , wherein the instructions that cause the processor to calculate the tip distance comprise instructions that, when executed, cause the processor to calculate the tip distance based on the separation distance between the pair of arms and a predetermined geometry between the positional sensor, the pivot joint, and the insertion tip of each arm. 
     
     
         16 . A method of assessing laxity of a joint including first and second bones, the method comprising:
 inserting a tensioner tool between the first and second bones while the tensioner tool is in a compressed configuration, the tensioner tool comprising a pair of arms pivotally coupled at a pivot joint, each arm including a proximal handle portion, a distal portion, and an insertion tip selectively coupled to the distal portion;   applying a force to at least one of the proximal handle portions, thereby causing the pair of arms to pivot about a pivot axis from the compressed configuration to an expanded configuration, wherein a tip distance between the insertion tips is greater in the expanded configuration than in the compressed configuration;   receiving, by a processor, force data related to the applied force from a force sensor coupled to one of the pair of arms;   calculating, by the processor, a distraction force exerted to the first and second bones by the insertion tips based on the force data;   receiving, by the processor, separation data related to a separation distance between the pair of arms from a positional sensor; and   calculating the tip distance based on the separation data.   
     
     
         17 . The method of  claim 16 , wherein for each arm, the distal portion comprises a through-hole configured to mate with a shaft of the insertion tip to selectively couple the insertion tip to the distal portion,
 wherein the insertion tip is configured to be received within a first end of the through-hole and extend substantially in a first direction from the distal portion; and   the insertion tip is configured to be received within a second end of the through-hole and extend substantially in a second direction, opposite the first direction, from the distal portion,   wherein the first direction and the second direction are substantially parallel to the pivot axis.   
     
     
         18 . The method of  claim 16 , wherein for each arm, the insertion tip is configured to rotate about a tip axis with respect to the distal portion when coupled to the distal portion, wherein the tip axis is substantially parallel to the pivot axis. 
     
     
         19 . The method of  claim 16 , where the positional sensor is disposed within the pivot joint. 
     
     
         20 . The method of  claim 16 , wherein calculating the tip distance comprises calculating the tip distance based on the separation distance between the pair of arms and a predetermined geometry between the positional sensor, the pivot joint, and the insertion tip of each arm. 
     
     
         21 . A tensioner tool for assessing laxity of a joint including first and second bones, the tensioner tool comprising:
 a pair of arms pivotally coupled at a pivot joint, each arm including a proximal handle portion, a distal portion, and an insertion tip selectively coupled to the distal portion, wherein the pair of arms are configured to pivot about a pivot axis between a compressed configuration for insertion between the first and second bones and an expanded configuration for distraction of the first and second bones in response to a force applied to at least one of the proximal handle portions, wherein a tip distance between the insertion tips is greater in the expanded configuration than in the compressed configuration;   a force sensor coupled to one of the pair of arms and configured to collect force data related to the applied force;   a positional sensor configured to collect separation data related to a separation distance between the pair of arms; and   a communications unit operably connected to the force sensor and the positional sensor, wherein the communications unit is configured to:
 receive the force data from the force sensor, 
 receive the separation data from the positional sensor, and 
 transmit the force data and the separation data to an external computing device.